Corrugated carton adhesive technology (on)

In 2004, China's adhesive production reached 3.79 million tons, an increase of 313.1%, sales of 29.2 billion yuan, and product quality is also rising. The adhesive's end use will continue to be closely linked to users of packaging and non-durable consumer products. They account for about 75% of the total amount of adhesives. The production and manufacture of corrugated cardboard boxes will remain the largest single application area for adhesives in the world. Starch-based products, due to their low cost and appropriate properties, will Dominance. Hot melt adhesives based on ethylene-vinyl acetate copolymers and styrene block copolymers, especially pressure sensitive tapes and labels, are gaining new uses in the packaging industry.

According to the prediction of the adhesive market demand from 2005 to 2010, the average annual growth rate is 11%. Among them, waterborne adhesives grew by 12%, hot melt adhesives increased by 15%, and environmental protection and energy-saving products accelerated development.

Affect the main indicators of adhesive

1. Viscosity

In the corrugated industry, viscosity is commonly used to characterize the fluidity of the adhesive. Factors that affect viscosity include: concentration, temperature, shear, storage time, resins, microbes, etc.

Low Viscosity: If the viscosity of the adhesive is too low, the moisture in it will quickly penetrate into the corrugated medium, causing the starch granules to fail to be fully gelatinized and the bond not being strong, while the corrugated paper coming out of the corrugating machine will be very dry and brittle.

High viscosity: If the viscosity of the adhesive is too high, the adhesive is difficult to penetrate into the interior of the paper, and the corrugated paper coming out of the corrugating machine will be very soft, causing subsequent processing and printing difficulties. At the same time, the consumption of starch will increase, and the fluidity of the adhesive will decrease. High-viscosity adhesives can be difficult to apply on high-speed single-sided machines.

2. Gelatinization temperature

The gelatinization temperature is the temperature at which the adhesive begins to thicken and produce adhesive forces.

The initial gelatinization temperature of corn starch is about 72 cC. The gelatinization temperature of the adhesive has a great influence on the adhesive strength, especially on the double-sided machine, which also has a great influence on the vehicle speed. The gelatinization temperature can be adjusted by adding caustic soda according to different corrugating machines and base papers.

If the gelatinization temperature is too high, it will cause the cardboard to open. The speed of the corrugator must be reduced to obtain sufficient energy, especially to produce multilayer cardboard. If the gelatinization temperature is too low, the adhesive is already gelatinized before it penetrates, the cardboard becomes brittle, the bonding is not strong, and it is possible that the adhesive has been pasted in the receiving slot. When the adhesive is stored for a period of time, the gelatinization temperature will increase.

3. concentration

The level of concentration directly affects the viscosity of the adhesive. Excess concentrations will result in excessive starch consumption, poor fluidity, uneven sizing, and poor adhesion. If the concentration is too low, the effect of adhesion will not be achieved.

4. Coating amount

Hand-striped veneer veneer, the amount of glue should not be too large, some employees in the actual production in order to avoid degumming, artificially increase the amount of glue, which is undesirable, must be strictly controlled. The amount of glue should be 380g-110g/m2. However, depending on the size of the corrugator, it is advisable to control the amount of glue and evenly coat the peak. As long as it is not degummed, the smaller the amount of glue, the better.

If the above indicators are not well controlled, it will lead to: (1) the paperboard is too wet and soft and difficult to print and follow-up; (2) the paperboard surface is corrugated and forms a "washboard"; (3) the paperboard is warped; ( 4) Cardboard delamination; (5) Speed ​​reduction; (6) Excessive consumption of starch.

5. Technical indicators

Pasting temperature: single-sided machine 58 °C -62 °C; double-sided machine 52 °C -60cC.
Starch consumption: single-sided machine 3g-5g/m2 double-sided machine 5g-7g/m2.

Viscosity: According to different corrugating machines and base paper, and the double-sided machine concentration should be higher than single-sided machine.

Comparison of the characteristics of different starches